Mushroom Hunter: Dr. Dennis E. Desjardin

Dennis Edmund Desjardin (1950-current) is an American mycologist who has been called the "Mushroom Guru of the West Coast". He was born in Crescent City, California and started his life's work at the age of three, collecting mushrooms with his grandparents. He attended San Jose State University for a time but dropped out to play jazz professionally.

A decade later, he attended San Francisco State University and graduated in 1983 with a B.S. in botany, and in 1985 with an M.A in ecology and systematic biology. His M.A. thesis (The marasmioid fungi of California) was supervised by Harry D. Thiers (see Mushroom Hunter: Dr. H. D. Thiers). Desjardin attended the University of Tennessee and graduated in 1989 with a Ph.D. in mycology. His Ph.D. thesis (The genus Marasmius from the southern Appalachian Mountains) was supervised by Ronald H. Petersen.

Dr. Dennis E. Desjardin (photo from the California Mushrooms website)

Desjardin worked as an assistant professor at a small liberal arts college in Ohio, and then worked his way up to a full professorship at San Francisco State University, where he worked until his retirement. He researched mycology in California and around the world, funded by numerous National Science Foundation grants. He conducted field studies and documented fungal diversity and the ethnomycology of indigenous cultures. He is the author or coauthor of over 150 scientific publications. He was appointed the director of SFSU's Harry D. Thiers Herbarium, and served as an associate editor for Fungal Diversity and Mycologia.

Dr. Desjardin spent 40 years documenting California's mushrooms, and coauthored California Mushrooms: The Comprehensive Identification Guide. He also researched ecology and the biogeography of fungal species associated with tropical and island habitats, bioluminescent fungi, and fungal systematics. He coauthored "Mushrooms of Hawai'i: An Identification Guide".  Desjardin discovered or co-discovered more than 300 fungal species, including species of luminescent mushrooms. Several mushrooms are named after him, including Agaricus desjardinii, Marasmius desjardinii, and Arcangeliella desjardinii. He retired from SFSU in 2021 and left academia to start a new career at Sempera as Chief Mycologist.

Dr. Desjardin (photo from the Sempera Organics website) 

I was interested to learn more about Dr. Desjardin because of his specialization in Californian mushrooms, and his interest in fungi around the world. I especially enjoyed reading about the naming of the SpongeBob SquarePants mushroom (Spongiforma squarepantsii). It's always a joy to see scientists having some fun! I also appreciated hearing that Dr. Thiers had named Gastrolactarius desjardinii to honor his colleague/protege.

Note: mushrooms are  renamed and reclassified continually as new information is discovered.

Learn More

• California Mushrooms website, which promotes California Mushrooms: The Comprehensive Identification Guide by Dennis E. Desjardin, Michael G. Wood, and Frederick A. Stevens. Select the About and Bios tabs for information about the book and its authors. https://www.californiamushrooms.us/index.html

An online version of the book is available on Mykoweb: https://www.mykoweb.com/CAF/index.html

• "Dennis E. Desjardin". Wikipedia website. Provides a brief biography of Desjardin and references. See: https://en.wikipedia.org/wiki/Dennis_E._Desjardin

• Desjardin, Dennis E.; Wood, Michael G.; Stevens, Frederick A. California Mushrooms: The Comprehensive Identification Guide (Timber Press, 2015). See:  https://www.californiamushrooms.us/index.html

• Harry D. Thiers Herbarium (SFSU). Dr. Desjardin was curator at the SFSU Herbarium for many years. 

• "Mushroom Lights up the Night in Brazil", EurekAlert!, July 6, 2011. Desjardin and his team at SFSU reclassifies bioluminescent mushroom from Agaricus gardneri to Neonothopanus gardneri. At the time, they were researching bioluminescence in mushrooms. See: https://www.eurekalert.org/news-releases/738500

• Hemmes, Don E; Desjardin, Dennis E. Mushrooms of Hawai'i: An Identification Guide (Echo Point Books & Media, 2016).

• Sempera Organics website. This company grows and produces mushrooms and mushroom-related products in a farm lab. Dr. Desjardin joined Sempera as its Chief Mycologist upon retirement from SFSU in 2021. https://semperaorganics.com/team/

• "Spongiforma squarepantsii". Wikipedia website. A fungus specimen whimsically named by Desjardin in 1984. See: https://en.wikipedia.org/wiki/Spongiforma_squarepantsii

Field Notes for August 2026

Welcome back to Field Notes!

August 1, 2026

Bobo Chronicles: Outing to Dracena Quarry Park. Bobo the Husky loves to explore new places. Mari gave me a tip about nearby Dracena Quarry Park. Rick, Bobo, and I visited this neighborhood park, which is nestled in a small canyon under a stand of redwood trees. We enjoyed a stroll in the deep shade, and a drink of cool water on one of the park benches. Small parks are one of the many things that I enjoy about living in the East Bay. Thanks, Mari!

Taking a breather under the redwoods

August 3, 2026

Look at This Slime Mold! My brother Dave sent me a picture of this glorious lemon-yellow slime mold. He was walking on North Douglas Island, near Juneau, Alaska, and checking out the beaver ponds. I haven't identified it. Could it be a Fuligo species? If so, Wikipedia provides this information:

Fuligo is a widespread genus of plasmodial slime mold in the family Physaraceae. These organisms are protozoans rather than fungi, but for historical reasons are sometimes treated as part of mycology.

Possibly, Fuligo septica, (also known as the dog vomit slime mold or scrambled egg slime). Fascinating!

Lemon-yellow slime mold - species unknown (photo by Dave Harris)

August 6, 2026

Happy Birthday to Rick! My wonderful husband just turned another year older. I think he is aghast at this bigger number, but he is just as hilarious, interesting, capable and cute as ever!

 

Contemplating the meaning of life

August 9, 2026

Field Trip to the Ferry Building.  Mari, Gaymond and I skipped the Over-the-Hills Gang hike this week and went rouge! It was such a beautiful day that we decided to take the ferry from Jack London Square to the Ferry Building instead. It's always great to get out on the water. We had some great views of the Port of Oakland, the container cranes, the underside of the Bay Bridge, and a whole variety of ships and crafts out on the water. Once we docked, we explored the Ferry Building and the Farmer's Market, and scoped out eateries for lunch.

Marine area along the Embarcadero

Farmer's Market outside the Ferry Building

We walked along the Embarcadero for a ways and explored some of the piers. There has been a lot of development since I last visited the area. I almost had a feeling that I was walking along some of the waterways in Europe!

Exploring the piers along the Embarcadero

Picture postcard on the waterfront (photo by Mari)

We returned to the Ferry Building and made our purchases at the Farmer's Market and Ferry Terminal, and ate outside in the sun (dim sum and empanadas). I picked up some empanadas to take home for the guys and Bobo the Husky, and we took the 1:05 ferry home. What a wonderful experience!

Intrepid explorers along the Embarcadero (photo by Gaymond)

August 11, 2026

Visit to Far West Fungi in the Ferry Building. While at the Ferry Building, I made a point of stopping in at Far West Fungi. They have an amazing selection of seasonal fresh mushrooms, bulk dehydrated mushrooms, and smaller packages of dried mushrooms. They also sell fun fungi-related merchandise, such as mugs, dish towels, and mushroom-growing kits.

I purchased packages of dehydrated Wood Ear, Porcini, and Morel mushrooms for some future cooking projects. Stay tuned!

Far West Fungi at the Ferry Building (#34)

Dehydrated mushrooms for sale

Fresh Wood Ear mushrooms on sale

August 15, 2026

Summer Read. I've been working through my summer reading list, and just finished "Garden of Lamentations" by Deborah Crombie (William Morrow, 2017). This is the seventeenth novel in the Duncan Kincaid/Gemma James series set in London. In this one, a crime takes place in one of its gated neighborhood gardens. Crombie  provides "A Short History of London Squares" in the back matter, which is all about the "network of enclosed garden squares winding through the city (of London) like interconnected necklaces of green".  Illustrator Laura Maestro provides the endpaper map for the story, which is charming and adds dimension to the mystery. Together they make the story all the more engaging (see both the book and map here)!

August 19, 2026

Happy Birthday to Aunt Char! My wonderful aunt is turning (a bigger number) and we plan to celebrate at her open house tomorrow. I really enjoyed spending time with her and my mom in Juneau, Alaska this year (in both winter and summer), and love going places with her here in the Bay Area (or wherever we travel). I'm grateful that she lives nearby and has such a wonderful outlook on life. My cousins will be here for the birthday bash (Jen from Idaho and Chris from Arizona), so that will be the icing on the cake!

Two sisters in the garden of life (summer 2026)

August 22, 2026

OTHG Hike to Marina Bay. Mari, Gaymond and I met up with the Over-the-Hills Gang hike at the Marina Bay in Richmond for the latest 55+ group hike. Marina Bay is located in the Richmond Inner Harbor, the former location of the World War II-era Kaiser Shipyards. We hiked the area a year ago, and enjoyed great views of the bay, wildlife in Meeker Slough, and proximity to multiple destinations (Marina Bay Park, Marina Bay Yacht Harbor and Yacht Club, the Rosie the Riveter Memorial, and a residential community along the shore). 

You Are Here - with so many great options nearby!

Maria Bay Park

Looking across Marina Bay to the Richmond Ferry Terminal

The sky was overcast and the temperature chilly, but we still had great views in all directions. The slough is a popular spot for birds to gather, so we had a chance to see pelicans, herons, ducks, geese, and more.

Surf break with Oakland in the background

Meeker Slough with Albany Hill in the distance

Cookie break at the half-way point

Anthony Fisher led our bay-side hike, and provided information about flora and fauna and delicious cookies at the half-way point. Mari, Gaymond, and I finished the hike with delicious food and conversation at the nearby Anh Restaurant & Bar. These hikes are so much fun - the pace is perfect and the company is excellent. Check the website to learn more about upcoming events offered by the East Bay Regional Park District.

Intrepid hikers at Marina Bay (photo by Mari)

Delicious lunch served family style - noodles and oxtail soup

August 24, 2026

Flora and Fauna at Marina Bay. While at Marina Bay, we saw lots of heron, ducks, Canadian geese, and lots of gulls and shore birds. We also say a Black Oystercatcher by the shore.

Duck, duck, duck, goose crossing

Family of ducks

Black Oystercatcher (photo by Mari)

August 28, 2026

Cooking with Mushrooms - Wood Ear. I purchased dehydrated Wood Ear mushrooms from Far West Fungi on our trip to the Ferry Building (see the August 11 entry above), and added them to a buckwheat noodle and dashi soup bowl. Wood Ear (Auricularia auricula-judae) are called jelly fungus because of their texture, but others are somewhat rubbery and gelatinous. The species grows throughout Europe and North America and is cultivated in China and East Asia. Far West Fungi grows them at their facility in Moss Landing, California.

Dehydrated Wood Ear Mushrooms

This was my first experience with Wood Ears, and I was struck with how much the reconstituted mushrooms resembled ears! They have a wonderful, crunchy texture, but not much flavor (they are typically incorporated in hot-and-sour soup, or used as a main ingredient in salads with a strong dressing). They were a little bland in my soup bowl, but did have an interesting crunch.

The rehydrated Wood Ears resemble ears

The soup was really bland, but the Wood Ear texture was very interesting

August 30, 2026 🌞

Landscape Maintenance. I spent a lot of time in the landscape cutting back our many grass clumps in response to the Fire Prevention inspection in July. The inspector felt the long, dry grasses could pose a fire risk. This gave me the opportunity to learn how to trim the grasses, and we are now back in compliance and fire safe. In between trimming up grasses, our family has been enjoying lots of outdoor living. We can be found out on the patio most afternoons, whether in the midst of a heat spell, or on cool, foggy days. Here are few other maintenance tasks for August:

✘ Weed the garden paths and beds (ongoing task). Note: as part of the grass clump clean up, I removed quite a few grasses that were starting to encroach on the paths. This widened the paths back to their original dimensions.

✘ Sweep debris from surfaces throughout the yard. 

✘ Clean up the stone walkway from the street to the house. Remove the weeds that pop up between the pavers, and that sneak into the planting beds and nearby cracks in the street (some people recommend spraying with vinegar to desiccate the leaves, although it may not kill the roots). Cut back the ground covers that spill over onto the pavers, and the grasses that spill over the path.

✘ Likewise, clean up the streetside, easement area for weeds and trash. There are some beautiful native plants in this area; prune or thin as needed to show them to their advantage. Add mulch or wood chips as needed. Note: I pulled a number of tall dandelion weeds from this area, but overall it looks like a lovely tapestry of plants.

🚫 Arrange for a pruning estimate to trim the oak. Note: we had the oak tree pruned last fall, and it still looks good – no branches overhanging the house or traffic. It will probably be good for another five years unless something changes. The rest of the trees and shrubs look good for now.

Dye Project: Dyer's Polypore

For this mushroom dyeing project, I'm using Dyer's Polypore (Phaeolus schweinitzii), which produces shades of yellow, gold, brown, orange, and olive green, depending on the material dyed and the mordant used. The best color is achieved using protein fibers like wool and silk.

Phaeolus schweinitzii is a polypore fungi (also called a bracket or shelf fungi). It may appear on tree trunks, or it may appear to be terrestrial when growing on underground roots or at the base of the host tree. The fruiting bodies are tannish with darker brown centers, and orange to pale margins on young specimens. As the fruiting bodies age, the pore surface turns from yellow to greenish yellow, the top becomes darker, and the yellow-brown flesh becomes harder and more wood-like. The pores bruise brown. The spores are white, elliptical, and smooth. The fungi is native to North America and Eurasia, and grows on conifers such as Douglas-fir, spruce, fir, hemlock, pine, and larch. The species is inedible, bitter, and mildly toxic.

Mature Dyer's Polypore at Tilden Park in January

Note: if you live in North America, Phaeolus hispidoides is the most up-to-date name. Recent phylogenetic studies have determined that the classic Phaeolus schweinitzii is restricted to Europe and Asia, and North American populations are now split into distinct regional species like Phaeolus hispidoides (common name, New World Dyer's Polypore). Since this change is fairly new, I plan to use P. schweinitzii and Dyer's Polypore in this post. 

Key Supplies

I'm using my usual dye equipment, including a convection burner, a non-reactive stainless steel dye pot, candy thermometer, strainer, cheese cloth, various plastic pails and containers for soaking and rinsing, a digital kitchen scale, stir stick, a mild pH-neutral soap (such as Synthropol or Professional Textile Detergent), rubber gloves, and a face mask. Additional supplies and equipment:

• Mushroom: Phaeolus schweinitzii - dried or fresh. I purchased one ounce (28 grams) of dried mushrooms from a supplier on Etsy (TheConstantForager). The recommended ratio of dye to fabric is 8% of Weight of Fabric (WOF). For example, 28 grams of silk (one ounce) would require 2.24 grams of Dyer's Polypore mushrooms (about .08 ounces).

Dried Dyer's Polypore mushroom

• pH test strips: to test how acidic or alkaline the dye bath is.

• Fabric: 100% protein fibers like wool or silk. I'm using two silk scarves and a silk/wool blend scarf from Dharma Trading, both of which have been scoured and mordanted with alum. For details, see Dye Project: Preparing Protein Fabric (Scour &  Mordant). 

• The silk scarves each weigh 1 ounce or 28 grams (total of 2 ounces or 56 grams). Note that one of the scarves was mordanted in April 2022, so it will be an interesting test of how long mordant lasts!

• The silk/wool blend scarf weighs .7 ounces or 20 grams.

• The recommended ratio of dye to fabric is 8% of Weight of Fabric (WOF); in this case, 8% of 28 grams is 2.24 grams x 2 and 8% of 20 grams is 1.6 grams. I should be able to dye all three items with the 1 ounce / 28 grams of dried mushrooms.

• pH Modifiers: You can easily shift the base yellow/gold colors using various mordants or additives as described below. I plan to only use fabric that is pre-mordanted with alum.
• No modifier / Alum: bright yellows and golds.
• Iron (Ferrous Sulfate): shifts colors to olive greens (use at 2% of fiber weight).
• Alkaline shift: adding washing soda can increase the pH and darken the yellow.

Extracting the Dye

Extracting color from mushrooms is similar to extracting color from plants. Chop the mushrooms into pieces, cover with water and soak overnight, bring to a simmer, and then simmer to extract the color. The process is the same whether you're using fresh or dried mushrooms.

Break the fresh or dried mushrooms and stems into pieces

First, break the mushrooms into small pieces (stems and caps). Cover with water in a non-reactive pot, and soak overnight. Color was released into the water almost immediately, and the pH registered 6 (mildly acid).

Soak mushroom pieces overnight (color starts being released almost immediately)

Next, bring the temperature to about 140 to 160 °F. This process takes about 30-60 minutes. Then let simmer at about 140 to 160 °F for about an hour until the color leaches out. The foam on top of the dye has a yellowish tint to it. I let the mushrooms cool and soak overnight in the dye to extract as much dye as possible.

Dyer's Polypore dye bath after simmering for an hour

Straining out the mushrooms from the extracted dye

Strain out the mushroom solids using a sieve with cheese cloth. I obtained about two quarts of extracted dye. The pH still registered 6 at this time (mildly acid).

The extracted Dyer's Polypore dye - look at that color!

Dyeing the Fabric

Dyeing fabric with mushrooms is very similar to dyeing with plants. Bring the dye bath to a simmer, pre-soak the silk or wool fabric or fiber in warm water, add the fabric to the dye pot, and simmer. One caveat is to make sure the temperature difference is very similar when going from one pot to another. For example, plunging cold silk into a hot dye bath causes shock shrinkage, uneven color, and weakened fibers. Better to add the cold silk to a cooled dye bath.

Place the extracted dye in a clean non-reactive pot and insert the thermometer. The pH still registered 6  at this time (mildly acid).

The extracted dye has a orangey-gold-brown cast to it

Bring the temperature of the dye bath to 140 to 160 °F. This typically takes about 30-60 minutes. I brought the temperature to 160 °F. Let simmer. Dyer's Polypore is more forgiving than some mushroom dyes, but the dye bath should not boil. While the dye bath is coming to temperature, pre-soak your wool or silk in warm water. This will improve how the fabric takes up the dye.

Soaking the three silk and silk/wool scarves in warm water

Add the fabric to the simmering dye pot and stir to distribute evenly. Add more water to cover the fabric if necessary. This will not dilute the dye; it just ensures a better of distribution of the dye to the fabric.

Distribute the fabric for an even uptake of the dye

Let the fabric simmer for at least 15 minutes, or longer to get the desired color, keeping the temperature between 140 to 160 °F. I simmered one of the silk scarves and the silk/wool blend scarf for 15 minutes, and the other silk scarf (the one mordanted in 2022) for an hour.

Remove the fabric and let it cool down, so you don't shock the fibers. I'm using a clean food container that once help chicken parts. Once cooled, hang to dry. You could rinse in lukewarm water before hanging to dry, but I'm waiting to give the dye longer to bond with the fabric.

Top: simmered for one hour
Bottom: simmered for 15 minutes

Two weeks later, wash with a mild pH-neutral soap, such as Synthropol or Professional Textile Detergent, to wash out unbound dye. Air dry out of direct sunlight. The resulting color is a strong orangey-gold.

The Results

The final results of dyeing with Dyer's Polypore mushrooms were quite stunning. I love the strong orangey-gold color (and was pleased how well the silk scarf that was mordanted in 2020 performed). While researching the project, many dyers commented on how prolific the dye bath is, enabling the dyer to continue dyeing multiple objects. I dyed three objects, and felt I could keep going. Because of that I decided to keep the dye bath to use in a future dye project.

Left hanger: silk and silk/wool scarves (15 minute simmer)
Right hanger: silk scarf (1 hour simmer)

Store the dye for future projects

Learn More

• Byrd, Margaret. "How to Make Natural Color from Dyer's Polypore". Color Quest, 2023. This video shows how to achieve different colors using Phaeolus schweinitzii and various mordants. https://youtu.be/_4adB4t4DpU

• Beeler, Julie. "The Mushroom Color Atlas: A Guide to Dyes and Pigments Made from Fungi". Discover the incredible spectrum of pigments and dyes that can be created from mushrooms. 

You can also use the online version of The Mushroom Color Atlas. Use the Index to filter for a specific fungus and see its batch notes and pigment studies (for example, Phaeolus hispidoides if you are in North America). This is a wonderful resource.

• Beeler, Julie. "Dyeing with Mushrooms". Bloom & Dye, January 31, 2019. This article describes the basic process of dyeing with mushrooms, using Phaeolus schweinitzii as an example. https://www.bloomanddye.com/journal/2019/2/1/dyeing-with-mushrooms

• Crook, Amy. "Dyeing with Phaeolus schweinitzii, Dyer’s Polypore". Fibreshed Vancouver Island, September 29, 2025. https://vancouverislandfibreshed.ca/dyeing-with-phaeolus-schweinitzii-dyers-polypore/

• Dawson, Cheryl. "Dyeing Protein Fibers with Mushrooms". North American Mycological Association. Provides a synthesis of published information about dyeing with mushrooms (revised January 2015).

• "How to Make Dye with Mushrooms: The Dyer's Polypore". Myra Made Color, December 17 2021. This video shows how to dye with Dyer's Polypore. https://youtu.be/T4TjnxFO3yw

• Hughs, Jenifer. Jenifer Hugh's Post, July 12, 2020. Mushroom and Lichen Dyers United. https://www.facebook.com/groups/mycopigments/posts/1618562678293998/

• McDonnel, Zoe. "How to Dye with Dyers Polypore / Phaeolus schweinitzii". Wildcraft Dyeing, 2020. In this video, a wildlife ecologist dyes yarn with Phaeolus schweinitzii. https://youtu.be/oeD4YQYq3tQ

• Phaeolus schweinitzii. Wikipedia: https://en.wikipedia.org/wiki/Phaeolus_schweinitzii

• "Testing 3 Different Mordant Methods with Phaeolus schweinitzii Mushroom Dye". Forest & Spirit, ~2018. https://forestandthespirit.wordpress.com/2016/06/30/dyeing-with-phaeolus-schweinitzii-mushroom/

• Vejar, Kristine. "Holiday Stitch Exchange: Dyeing with Mushrooms". A Verb for Keeping Warm, December 3, 2014. https://www.averbforkeepingwarm.com/blogs/news/16127352-holiday-stitch-exchange-dyeing-with-mushrooms?srsltid=AfmBOop_djXWil1ISwpm9-FNQuWwiQWf2-swMzBLI2PjLiJ4nWV6WIK8